Vibratory stone polisher

ABSTRACT

A vibratory stone polisher comprising a base and a laminated arm pivotally mounted on the base to be reciprocally displaced by means of an electromagnet, a bracket connected to the arm and to the base for receiving a cylindrical stone polishing barrel and an arrangement of springs for varying the bilateral resistance to displacement applied to the arm thus to vary the speed of polishing.

United States Patent [1 1 McDonald Nov. 6, 1973 1 1 VIBRATORY STONE POLISHER [76] Inventor: Joseph A. McDonald, 8718 Old State Ave., Farewell, Mich.

48622 n W. V Vows, an

22 Filed: June 28,1971

21 App1.No.: 157,133

[52] [1.8. CI. 51/163, 259/72 [51] Int. Cl B24b 31/06 [58] Field of Search 51/7, 163, 17, 6;

259/D1G. 42, 72, 73, 75; 29/90 R, 90 B [56] References Cited UNITED STATES PATENTS 6/1931 Clark 259/72 10/1963 Dahlquist et a1 51/163 1/1965 Moore 51/163 3,637,190 1/1972 lsaacson 259/72 Primary ExaminerHarold D. Whitehead Assistant Examiner-Nicholas P. Godici Attorney-McGlynn, Jr. et a1.

[57] ABSTRACT A vibratory stone polisher comprising a base and a laminated arm pivotally mounted on the base to be reciprocally displaced by means of an electromagnet, a bracket connected to the arm and to the base for receiving a cylindrical stone polishing barrel and an arrangement of springs for varying the bilateral resistance to displacement applied to the arm thus to vary the speed of polishing.

7 Claims, 5 Drawing Figures PAIENTEDuov 6 ms 3.769.758

I N VEN TOR.

ATTORNEYS PATENTEDNUV 6 ms 3,769,758

SHEET 2 CF 2 1 N VEN TOR.

AT TO RN EYS VIBRATORY STONE POLISI-IER This invention relates to vibratory polishing apparatus and more particularly to a stone polisher of the type which employs a reciprocating rather than rotating drive mechanism.

It is well known that various stones and other materials can be slowly and gradually polished to a smooth attractive surface finish by light abrasion. This process of abrasion and polishing is quite often carried out by means of an apparatus which includes a closed barrel into which the stones or other materials to be polished are placed along with an abraiding medium, and a motor and belt drive apparatus for continuously rotating the barrel. This combination of apparatus is often known as a tumbler as it results in the continuous rotation of the barrel about its own axis of symmetry, thus turning the stones and abrading medium over and over within the barrel and producing the polishing function by tumbling. This process of polishing is generally regarded as being comparatively slow; for example, the polishing of ordinary field stones may require several weeks of continuous tumbling.

In accordance with the present invention a polishing apparatus is provided which is characterized by a reciprocating oscillatory motion of the stone container or barrel as opposed to the rotating barrel motion described above and in which the polishing function is typically accomplished in a relatively rapid fashion thus to realize the desired state of polish in a relatively short period of time. In accordance with the invention the stone container or barrel is operatively connected to a pivotal arm which is reciprocally and pivotally displaced at a predetermined frequency, the arcuate pivotal motion of arm being such as to produce a reciprocal motion of the barrel which induces a substantially circular or closed loop flow of stones and abrading materials within the barrel. In addition, the arm is provided with mechanical spring means which produce a bilateral spring resistance on the displacement ofthe arm, this spring resistance being selectively variable thereby to provide selective variation in the amplitude of reciprocal displacement and, resultingly, thespeed of stone flow in'the barrel.

In accordance with a preferred embodiment of the invention which is set forth hereinafter in great detail a vibratory stone polisher embodying the invention comprises a base, a pivotal arm of steel laminations pivotally mounted on the base and being pivotally secured at one end to a barrel support bracket. The barrel support bracket is also secured to the base by means of a resilient pivot connection.

An electromagnet is operatively disposed adjacent the arm such that energization of the electromagnet produces a reciprocal pivotal translation or displacement of the arm thus to vibrate the bracket and the barrel which may be secured releasably to the bracket. In addition, a shaft carried by the base extends upwardly through the laminated pivotal arm and carries a pair of springs which are disposed on opposite sides of the arm to produce a bilateral spring bias for resisting translation of the arm. The shaft may be threaded so as to receive a wing nut or other similar device to permit the springs to be variably compressed thus to mechanically vary the resistance to pivotal displacement of the arm.

The various features and advantages of the present invention will become more-apparent from a reading of the following specification which sets forth an illustrative embodiment of the invention in detail. This specification is to be taken with the accompanying drawing of which:

FIG. 1 is a side view, partly in cross section of an illustrative embodiment of the invention;

FIG. 2 is a plan view, partly in cross section, of the embodiment of FIG. 1;

FIG. 3 is a view taken along a section line 33 of FIG. 1 and in the direction indicated;

FIG. 4 is a view taken along a section line 4-4 of FIG. 1 and in the direction indicated and FIG. 5 is a simple schematic diagram of the electromagnet energization circuit for the embodiment of FIG. 1.

Referring now to FIGS. l and 2 there is shown a vibratory stone polisher 10 comprising a flat base 12 of wood or suitable material having secured to the upper surface thereof a steel plate 14. The plate 14 in turn has secured thereto such as by welding a series of longitudinally extending laminations 16 which are mechanically and pivotally connected to an upright stack of steel laminations 18. The upright stack 18 acts as a pivotal support for an arm 20 which again comprises a series of rectangular steel laminations as best shown in FIG. 2. The point of pivotal displacement of the arm 20 relative to the upright stack 18 is indicated at 22 and best comprises-a simple mechanical fulcrum arrangement which may be cushioned by means of a rubber mounting 27. The end of the arm 20 to the left of the fulcrum point 22 as shown in FIG. 1 is preferably riveted together and provided with a pair of outturned wing-like flanges 24 which are secured to tension springs 26 connected between the flanges 24 and the base 12. Thus, the springs 26 tend to place a force on the arm 20 holding it down onto the pivotal fulcrum point of upright .stack 18, this tension also placing a very slight bias on ise I rel support bracket 32 and the arm 20. The other end of the arcuate bracket 32 is secured to a somewhat resilient metal standard 34 by means of rivets 36. The standard 34 may be suitably fastened to the base 12 by screws or such other means as proves advantageous.

The bracket 32 is adapted tp receive a generally cylindrically shaped barrel 38 which as best shown in FIG. 2 has an opening 40 in the upper wall portion thereof and is characterized by a smooth and non-flat (in the example shown, round) interior surface 42 which may or may not be lined in any suitable fashion to receive the stones and other materials to be polished as well as the abrading grits. Barrel 38 is further provided with inwardly sloping end walls 44 as best shown in FIG. 3 to prevent the stones .or other materials being polished from piling up at the end walls. An arcuate strip of rubber or other shock absorbingelastomeric material 46 is cemented to the inside surface of the bracket 32 to dampen noise or other vibration which may occur between the bracket 32 and the barrel 38.

To removably secure the barrel 38 to the bracket 32 the upper end of the bracket is turned back on itself as shown at 48 and may be hooked inside of the opening 40 of the barrel 38 as shown in FIGS. 1 and 2. At the other end of the bracket 32 a spring arrangement having a looped type handle 50 and a hook 52 is provided for catching the other side of the opening 40 in the barrel 38, the grasping loop 50 and hook 52 being formed integrally and secured to a small tension spring 54 which is permanently connected to the outer end of the bracket 32 adjacent the rivet 36.

The apparatus involving and immediately adjacent to the bracket 32 thus far described defines a pivotal arrangement for the barrel 38 which translates reciprocal displacement of the arm 20about the fulcrum point 22 into a reciprocal displacement of the bracket 32 about a pivot point which is substantially at the location of the rivet 36. It will be noted in FIG. 1 that the point of interconnection between the arm 20 and the tongue 30 of the bracket 32 is higher than the pivot point 36 relative to the base 12 and further that the arm 20 is not at the top dead center position when at rest but rather is displaced slightly counter clockwise from this top dead center position. Thus, upon displacement of the arm 20 in the clockwise direction from the position shown in FIG. 1 the bracket 32 and the barrel 38 is pushed to the right as well as downwardly from the position shown in FIG. 1. This compound displacement is permitted by the-resilient nature of the standard 34 as well as the pivotal connection which is defined by the elements immediately adjacent and secured together by the rivet 36 thus to produce a reciprocal and vibratory action tending to rotate stones and other materials in the barrel 38 in a closed loop clockwise direction viewed from the end of the barrel as shown in FIG. 1. The barrel 38, of course, does not rotate at all; that is to say it does not rotate in a continuous fashion but rather is pushed downwardly and outwardly away from the stones to promote a relatively rapid and circulatory tumbling action of the'stones over one another within the barrel.

Referring again to FIGS. 1 and -2 the wedge shaped notch 28 receives the flat tongue 30 of the bracket 32, these two elements being held togetherby means of springs 56 which extend betweenL-shaped brackets 55 mounted on the arm 20 and a plate 58 having suitable apertures and being welded or riveted 'to the tongue 30 as desired.

Looking now especially to FIGS. 1, 2 and 4 the means for causing the reciprocal and pivotal displacement of the arm 20 it is shown to comprise an electromagnet having a wound coil 60 of relatively fine wire and being disposed on a laminated core 62. The core 62 is disposed in the upright position and is magnetically and mechanically interconnected with the base laminations 16. A suitable coil 60 comprises about 2,500 turns of No. 24 wire. The core 62 is vertically spaced from the laminations of the arm 20 as shown in FIGS. 1 and 4 to define an air gap in the magnetic path which in total is defined by the core 62, the base lami-. nations 16, the upright stack 18 and the arm 20. The coil 60 is connected through a half wave rectifying diode 64 to a standard two-conductor cord 66 which is employed to connect the coil 60 to a standard 115 volt ac outlet to provide current at the standard 60 cycle frequency. An on-off switch68 may be provided in the cord 66 between the coil 60 and the two terminal plug 70 as shown in FIG. 2.

Referring to FIG. 5' it can be seen that the diode 64 being in series with the coil 60 has the effect of half wave rectification with respect to the current flowing from the ac source to the coil 60. Thus, the current waveform through the coil 60 is generally characterized as a series of half wave rectified pulses being substantially spaced from one another by half cycle time intervals. The arm 20 is sequentially and repetitively attracted toward the core 62 with each surge of current through the coil 60 thus tending to displace the arm 20 in the clockwise direction as shown in FIG. 1. With each relaxation of current between the half wave rectified pulses the arm 20 is released and moves back in the counter clockwise direction at an amplitude which is set by means hereinafter described.

As again as best shown in FIGS. 1 and 4 the spring forces which are exerted on the arm 20 to resist displacement are provided by an apparatus which comprises an upright threaded shaft 72 which is suitably secured to the plate 14 on the base 12. Shaft 72 extends upwardly through a hole 74 in the laminations of the arm 20. A suitable arrangement of nutsand washers is provided to entrap coil springs 76 and 78 on the shaft 72 between the opposite horizontal surfaces of the arm 20 thus to produce a bilateral spring force resisting pivotal displacement of the arm in either the clockwise or counterclockwise direction. Accordingly, upon energization of the coil 60 to attract the arm 20 toward the armature 62 the spring 78 isfurther compressed while the spring 76 is correspondingly decompressed. Upon relaxation of the current through the coil 60 the. spring 76 and 78 tend to seek an equilibrium condition whereby the arm 20 is displaced back in the counterclockwise direction. The degree of compression of spring 76 and 78 may be selectively varied by means of a wing nut 80 which is threaded onto the shaft 72 thus to readily and infinitely vary the amplitude of the vibration or displacement of arm 20. This control over pivotal dis-placement amplitude also controls the pivotal displacement amplitude of the barrel 38 and thus the speed at'which the stones are tumbled'therein.

To give the stone polisher 10 an attractive appearance a lightweight plastic cover 82 may be placed over the mechanism'inclu'ding the arm 20 and'the electromagnetic coil 60. The cover 82 is preferably provided with an opening 84' through which the amplitude adjustment shaft 72 and the wing nut 80 extend as shown in FIGS. 1 and 4. Wooden rails 86 may be disposed on the base 12 to provide an anchor for the cover 82 in combination with ordinary wood screws not shown. In addition the base 12 ispreferably provided with rubber shock absorbing 'feet 88 to damp out any vibration which might otherwise be transmitted from the base 12 to any surface on which it is placed.

The geometry of the barrel 38 is an important feature of the vibratory stone polisher l0 and preferably is of the configuration shown in FIGS. 1, 2 and 3, that is, of generally cylindrical configuration having an opening 40 in the top and having inwardly sloping sidewalls 44 such that the stones or other materials being polished are tumbled even though they may ride up slightly on the end wall surfaces during the abrading process.

By way of a description of operation the methods by which abrading and polishing are accomplished are well known to those skilled in the art and thus will not be repeated here in any detail. Suffice it to say that one loads a suitable number of stones to be polished, preferably in a variation of sizes, into the barrel 38 along with a suitable quantity and quality of abrading grit and water. The barrel 38 is then placed into the bracket 32, secured by the turned back portion 48 of the bracket as well as the hook 52. The switch 68 is then turned on to excite the coil 60 with half wave rectified pulses which set up the reciprocal oscillatory motion of the arm 20 and the barrel support bracket 32 as previously described. The stones and grit then begin the process of closed looped rotation or flowing over one another in a clockwise direction as viewed from the vantage point of FIG. 1. The tumbling and abrading of the stones is continued and checked periodically as necessary to produce the desired end result. The barrel 38 is preferably formed of plastic or fiberglass or other suitable material and because of the abrading action therein is preferably lined with a wear-resistant material.

It is to be understood that the description given in the foregoing specification is illustrative in nature and is not to be construed in a limiting sense.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

l. Vibratory polishing apparatus comprising: a base, a rigid arm pivotally mounted on the base, electromagnetic means for reciprocally and pivotally displacing the arm relative to the base, a support bracket pivotally connected at one side to the base and at the other side to the arm to be reciprocally displaced thereby through a substantially vertical path upon pivotal displacement of said rigid arm, a polishing barrel having a non-flat interior surface and being attachable to the support bracket to be displaced therewith, and spring means for mechanically bilaterally resisting the displacement of the arm.

2. Apparatus as defined in claim 1 wherein the spring means includes means for selectively varying the spring resistance thereof for tuning the amplitude of displacement of the arm.

3. Apparatus as defined in claim 2 wherein the arm comprises a series of laminations and the electromagnetic means comprises a coil having a laminated core which is spaced from the arm by means of an air gap.

4. Apparatus as defined in claim 3 wherein the spring means comprises a threaded shaft secured to the base and extending through an aperture in the arm and a pair of springs disposed on the shaft and engaging opposite sides of the arm.

5. Apparatus as defined in claim 1 wherein the support bracket is generally arcuate and is pivotally connected to the resilient standard which in turn is connected to the base, the barrel being generally cylindrical in configuration and disposed on said bracket with the cylindrical axis thereof perpendicular to the arm and to the direction of displacement thereof and having an opening in the top thereof.

6. Apparatus as defined in claim 5 wherein the barrel has inwardly tapering end walls spaced apart along said cylindrical axis.

7. Vibratory polishing apparatus comprising: a base, a barrel support bracket, and a cylindrical polishing barrel removably secured to the bracket, a spring standard connected between one side of the bracket and the base for resilient support of the bracket and barrel relative to the base, a rigid arm of low magnetic reluctance material mounted for substantially vertical reciprocal pivotal displacement relative to the base, means pivotally securing the free end of the rigid arm to the other side of the bracket such that pivotal displacement of said arm results in vibratory displacement of the barrel substantially perpendicular to the cylindrical axis of the barrel, bidirectional spring means connected between the base and the rigid arm for resiliently resisting displacement thereof, means for adjusting the spring force of the bidirectional spring means for controlling the amplitude of vibratory displacement of the barrel, and electromagnetic motor means for causing intermittent pivotal displacement of said rigid arm relative to the base. 

1. Vibratory polishing apparatus comprising: a base, a rigid arm pivotally mounted on the base, electromagnetic means for reciprocally and pivotally displacing the arm relative to the base, a support bracket pivotally connected at one side to the base and at the other side to the arm to be reciprocally displaced thereby through a substantially vertical path upon pivotal displacement of said rigid arm, a polishing barrel having a non-flat interior surface and being attachable to the support bracket to be displaced therewith, and spring means for mechanically bilaterally resisting the displacement of the arm.
 2. Apparatus as defined in claim 1 wherein the spring means includes means for selectively varying the spring resistance thereof for tuning the amplitude of displacement of the arm.
 3. Apparatus as defined in claim 2 wherein the arm comprises a series of laminations and the electromagnetic means comprises a coil having a laminated core which is spaced from the arm by means of an air gap.
 4. Apparatus as defined in claim 3 wherein the spring means comprises a threaded shaft secured to the base and extending through an aperture in the arm and a pair of springs disposed on the shaft and engaging opposite sides of the arm.
 5. Apparatus as defined in claim 1 wherein the support bracket is generally arcuate and is pivotally connected to the resilient standard which in turn is connected to the base, the barrel being generally cylindrical in configuration and disposed on said bracket with the cylindrical axis thereof perpendicular to the arm and to the direction of displacement thereof and having an opening in the top thereof.
 6. Apparatus as defined in claim 5 wherein the barrel has inwardly tapering end walls spaced apart along said cylindrical axis.
 7. Vibratory polishing apparatus comprising: a base, a barrel support bracket, and a cylindrical polishing barrel removably secured to the bracket, a spring standard connected between one side of the bracket and the base for resilient support of the bracket and barrel relative to the base, a rigid arm of low magnetic reluctance material mounted for substantially vertical reciprocal pivotal displacement relative to the base, means pivotally securing the free end of the rigid arm to the other side of the bracket such that pivotal displacement of said arm results in vibratory displacement of the barrel substantially perpendicular to the cylindrical axis of the barrel, bidirectional spring means connected between the base and the rigid arm for resiliently resisting displacement thereof, means for adjusting the spring force of the bidirectional spring means for controlling the amplitude of vibratory displacement of the barrel, and electromagnetic motor means for causing intermittent pivotal displacement of said rigid arm relative to the base. 